Field of the Invention
The present invention is directed in general to communications systems and methods for operating same. In one aspect, the present invention relates to devices and methods for manipulating the mutual coupling and the correlation between antennas on a handset without the need to change the physical distance between the antennas or to change their orientation.
Description of the Related Art
Future applications require technologies that provide higher throughput with broadband communications. Multiple-antenna technologies have promised system improvement such as to cover the future needs of throughput and bandwidth. In some cases, a limitation in implementing multiple antennas in the handset is the increased coupling that takes place between the antennas as the operating frequency becomes lower and/or as the handset device becomes smaller. The mutual coupling between the antennas also has a negative impact on the correlation between the antennas, which directly translates into an overall system performance degradation.
Researchers have introduced diversity techniques such as spatial diversity, where the antennas are kept apart at the largest distance possible, polarization diversity techniques, where the antennas are designed to have orthogonal polarizations, and pattern diversity techniques, which means that the two antennas have maximums in their patterns that are not in the same direction as well as other diversity techniques. However, these techniques have their limitations, especially for implementation in the confined volume of the handset. Therefore, to realize more benefits of multiple-antenna systems, novel approaches need to be developed to manipulate the mutual coupling and correlation between the antennas on the handset.